Abstract: In a power transmission device, guide elements, which are to be secured to a mounting portion of a driver, are axially fitted through and circumferentially arranged on a brake element concentrically disposed around a hollow tubular shaft which is adapted to be fitted on an output rotary shaft of the driver for rotation therewith. The brake element is urged by springs engaging the respective guide elements, toward an operating element which axially moves the brake element. An input element concentrically secured on the hollow tubular shaft and a friction plate concentrically and rotatably disposed thereabout have first and second openings, respectively, which are axially alignable with the guide elements, whereby the guide elements and the springs can be mounted into and removed from the power transmission device, through the aligned first and second openings.

Abstract: An axially displaceable brake element is arranged in facing relation to an operating element which is pivotable through a predetermined circumferential angle, with clutch balls engaged in grooves having slanted bottoms and formed in mutually facing side surfaces of the brake element and the operating element. Pivoting of the operating element causes displacement of the brake element relative to the operating element. A friction plate is spline-fitted on an output hub so as to be displaced only in the axial directions and arranged selectively for frictional contact with the brake element or the operating element. Displacement of the brake element toward the operating element causes frictional engagement of the friction plate with an input hub to obtain engagement of the clutch, while displacement of the brake element away from the operating element causes frictional engagement of the friction plate with the brake element to obtain disengagement of the clutch and braking of the output hub.